KR20170053577A - Improved method of material deposition - Google Patents

Abstract

A charged particle processing method and apparatus comprise the formation of a protective layer made of at least two kinds of materials. The two kinds of materials can be mixed together or can be deposited as an individual layer formulated and arranged according to the material properties of a sample. Accordingly, the present invention can prevent a surface artifact and a tilt change.

Description

[0001] IMPROVED METHOD OF MATERIAL DEPOSITION [0002]

The present invention relates to charged particle beam-induced deposition, and more particularly to precursor gas compositions for FIB and SEM beam chemistry.

In the prior art, materials are typically deposited on a sample surface through ion beam induced deposition (IBID), typically performed in a focused ion beam (FIB) instrument, and electron beam induced deposition (EBID), typically performed in a scanning electron microscope Is known. According to known methods, the sample is placed in a mobile particle chamber of a charged particle beam device - typically a FIB system or a SEM system. The charged particle (or other) beam is applied to the sample surface in the presence of a deposition gas (often referred to as a precursor gas). The precursor gas layer is adsorbed on the surface of the sample. The thickness of the layer depends on the balance of adsorption and desorption of the gas molecules on the sample surface, which ultimately depends on, for example, the partial gas pressure, the substrate temperature and the sticking coefficient. The thickness of the resulting layer may vary depending on the application.

Material deposition can be performed using a variety of different gas precursors depending on the application. For example, tungsten hexacarbonyl (W (CO) ₆ ) gas can be used to deposit tungsten, and naphthalene gas can be used to deposit carbon. A precursor gas of TEOS, TMCTS or HMCHS gas may be used with an oxidizing agent such as H ₂ O or O ₂ to deposit silicon oxide (SiO _x ). For the deposition of platinum (Pt), (methylcyclopentadienyl) trimethylplatinum gas may be used.

The material deposits obtained from these different precursors have different properties. For example, IBID Pt deposited using (methylcyclopentadienyl) trimethyl platinum precursor The material tends to be "softer". That is, these softer materials are more susceptible to subsequent ion beam sputtering than IBID carbon or tungsten layers, respectively, which are "harder" obtained using naphthalene or W (CO) ₆ . The silicon oxide layer using precursors of TEOS, TMCTS or HMCHS gas with oxidizing agents such as H ₂ O or O ₂ tends to be more "medium" hardness. The relative "hardness" or "age" of the material depends on the angle of incidence of the beam. In some material pairs, a "harder" material becomes more flexible at different incidence angles. Other differences also exist. For example, when a platinum film is used as a sacrificial cap prior to FIB sectioning (e.g., occurring during TEM fabrication), the soft nature of the film tends to cause a smooth transverse cut surface. In contrast, carbon films are very rigid and tend to produce artifacts on the cut surface that are known as "curtaining ". In addition to the hardness characteristics, the rate of growth of these different deposition precursors may also be an important factor for various applications.

The following are examples of various classes of gas precursors. For example, the Class C etchant may include oxygen (O ₂ ), nitrous oxide (N ₂ O), and water. The metal etchant may include iodine (I ₂ ), bromine (Br ₂ ), chlorine (Cl ₂ ), xenon difluoride (XeF ₂ ) and nitrogen dioxide (NO ₂ ). Dielectric etchant may comprise a xenon difluoride (XeF _2), nitrogen trifluoride (NF _3), acetic acid (TFAA) in acetamide (TFA) and trifluoroacetic acid trifluoroacetate. Metal deposition precursor gas (methylcyclopentadienyl) trimethyl platinum, tetrakis (triphenylphosphine) platinum (0), (0), tungsten hexa-carbonyl (W (CO) _6), tungsten hexafluoride (WF ₆ ), molybdenum hexa-carbonyl (Mo (CO) _6), dimethyl (acetylacetonate) gold (III), tetraethylammonium tetraethylorthosilicate, including orthosilicate (TEOS), and water (H ₂ O) ( TEOS). The dielectric deposition precursors include tetraethylorthosilicate (TEOS), including tetraethylorthosilicate (TEOS), water (H ₂ O), hexamethylcyclohexasiloxane ((HMCHS) + O ₂ ), and tetramethylcyclotetrasiloxane TMCTS) + O ₂ ). The carbon deposition precursor may include naphthalene and dodecane (C ₁₂ H ₂₆ ), and the planar layer remover may include methyl nitroacetate. Although they are many examples of gas precursors available, a number of other precursors are also available and are usable.

Beam induced deposition is used in a wide variety of applications to deposit materials on a target surface of a sample, such as a semiconductor wafer. The material can be used to form a capping material for milling a variety of reasons, for example, thin film surfaces, electrical connections, protective coatings for characterization and analysis of semiconductor features, and high-aspect ratio structures (e.g., vias) Lt; / RTI > However, if there is a significant difference between the hardness of the sample and the deposited capping material, it may be difficult to obtain the desired structure, form and surface properties of the sample to be produced. For example, it may be difficult to control a sloped surface in the formation of a milled structure, since different sputter rates of materials may cause an inclination change at the interface between the materials. In addition, artifacts can occur on FIB milled surfaces during a sectioning process to produce morphological characterization and analytical samples.

Techniques using FIB systems are known for making ultra thin film samples for shape characterization and analysis, where it is important to minimize the occurrence of surface artifacts introduced during the milling process.

Because semiconductor geometries continue to shrink, manufacturers increasingly rely on transmission electron microscopy (TEM) to monitor manufacturing processes, analyze defects, and investigate contact layer morphology. Transmission electron microscopy allows observers to view nanometer-scale sized features. In contrast to scanning electron microscopy (SEM), which only images the surface of the material, the TEM also enables the analysis of the internal structure of the sample. In the TEM, a broad beam impinges on the sample, and electrons passing through the sample are detected to form an image of the sample. The scanning transmission electron microscope (STEM) combines the principles of TEM and SEM and can be performed on any instrument. The STEM technique scans a very finely focused beam of electrons across the sample in a raster pattern. The sample should be thin enough so that a large number of electrons in the primary beam travel through the sample and exit from the opposite side.

Since the sample must be very thin to observe with a transmission electron microscope (whether TEM or STEM), the preparation of the sample can be difficult and time consuming. As used herein, the term "TEM" refers to TEM or STEM, and reference to the preparation of a sample for TEM is also understood to include preparation of a sample for observation on STEM. The term "STEM" as used herein also refers to both TEM and STEM.

There are several ways to make thin samples for observation by TEM or STEM. Some methods entail extracting the sample without destroying the entire material from which it is extracted. Another method is required to destroy the material to extract the sample. Some methods provide for the extraction of thin samples referred to as lamella. The lamellar may require thinning prior to TEM or STEM observations.

Lamina samples for TEM observations are typically less than 100 nm thick, but for some applications the sample should be considerably thinner. For advanced semiconductor fabrication processes at design nodes below 30 nm, the sample needs to be less than 20 nm thick to avoid overlap between small structures. Analysis of some applications, such as subsequent-node semiconductor devices, requires a lamella with a thickness of 15 nm or less to isolate a particular device of interest. The current method of thinning lamellas is difficult and not robust. Thickness variations in the sample can cause sample bending or bending, excessive milling, or other fatal defects that can destroy the lamella. For such thin samples, fabrication is an important step in TEM analysis, which determines the quality of the structural characterization and analysis of the smallest and most important structures.

It is known to provide a protective layer that is deposited on the desired lamella location prior to thinning to protect the area of interest on the sample from exposure to the ion beam and to prevent bending or warpage. In one commonly used fabrication technique as shown in Figures 1-3, a protective layer 22 of a material, e.g., tungsten, carbon, or platinum, is first deposited using electron beam or ion beam deposition, as shown in Figure 1 Is deposited over the region of interest on the top surface (23) of the sample body. Then, as shown in FIGS. 2 and 3, a large amount of material is milled from the front and rear portions of the region of interest using a focused ion beam having a correspondingly large beam size, using a high beam current. The remaining material between the two milled areas 24 and 25 forms a thin vertical sample compartment 26 comprising the area of interest. Typically, the region of interest is contained at 200-300 nm above the sample surface. The area 25 milled on the back surface of the area of interest is shown to be smaller than the front area 24. This smaller milled area 25 is basically intended not only to shorten the time but also to allow the finished sample to fall into the larger milled area 24 to remove the sample compartment 26 from the sample body Thereby preventing difficulties. The sample compartment 26 can then be cut from the sample body using a focused ion beam and then lifted in a well known manner, for example using a micro manipulator. The sample compartment 26 is then typically transferred to a TEM grid and thinned. The sample compartment 26 can then be analyzed using a TEM or other analytical tool.

Significant problems occur in the manufacture of ultra-thin (<30 nm thick) TEM samples. For example, the platinum protective layer on the region of interest is too soft, often broken during lamellar thinning, and is completely consumed by peripheral erosion from the ion beam tail before lamellar thinning is complete. A harder material layer can withstand erosion better than a softer material, but can cause undesirable artifacts on the cross-section of the lamella.

Figures 4 and 5 show examples of problems in the preparation of ultra-thin samples. As shown in FIG. 4, the cross-section of the lamellar sample 30 is shown as being fabricated with a soft Pt cap 32 deposited on a rigid diamond substrate 34. If the lamellar 30 is fabricated by thinning to the required thickness dimension, such hardness mismatch will cause erosion of the softer Pt cap 32, which is faster than the harder diamond substrate 34. This combination will prevent the user from thinning the lamella as desired because the protective cap 32 will eventually be completely consumed before the substrate 34 is sufficiently thinned. Conversely, as seen in FIG. 5, the cross-section of the lamella sample 36 is shown to be made with a hard carbon cap 38 positioned on the soft copper substrate 40. In this example, an undercutting 42 may be observed because the softer substrate 40 is consumed faster than the harder cap 38. This can lead to premature failure of the lamella as well as cross-cut surface artifacts such as "cutting ".

Cutting is an artifact that causes the surface of the sample to ripple or become uneven. Cutting can occur for a variety of reasons. If the sample is made of different materials with different sputter rates and is non-homogeneous, the more rigid material may form a resistive area that protrudes slightly from the cross-section. These protrusions shield these lower regions, which cause vertical streaks that propagate downward. Figure 6 shows a sample 44 with a silicon substrate comprising a tungsten protective layer representing the cutting. A "curtain" occurs because the tungsten is harder than the silicon substrate or is more resistant to sputtering from the ion beam. This results in a slightly protruding shape from the cross-section of the substrate. The harder protruding tungsten essentially leaves the vertical protrusion of the tungsten and shields the substrate just below it. Alternatively, some hard capping material forms a ripple-like or straight line pattern when exposed to the ion beam, even though the capping material itself is internally homogeneous. FIG. 7 shows a sample 46 with a silicon substrate comprising a carbon protective layer showing the cutting. When cross-sectional milling is performed, the carbon layer material gradually assumes a highly textured surface. Thus, in this example, the topography of the carbon layer causes the cutting. A top-down thinning of a sample with this type of structural or dense deformation results in a vertical ridge or deformation of the sample from a more dense material (i.e., a metal line) near the sample top (where the top is defined as being closest to the ion beam source) So as to propagate in a direction parallel to the ion beam direction. Cutting is often observed in semiconductor materials, in which a large number of patterned layers of material often have a lower sputtering yield, blocking substances of higher sputtering yield. Cutting can also be observed in materials that exhibit areas of different topography where the change in sputtering yield depends on the milling angle of incidence. A sample with void also induces the curtain. Cutting artifacts reduce the quality of TEM imaging and limit the minimum useful sample thickness.

Another type of artifact is referred to as a "golf tee. &Quot; For example, a layer of tungsten or carbon on top of the region of interest on a sample, typically a material such as silicon. The capping material and the silicon substrate have different "hardness" (resistance to sputtering from the ion beam), resulting in a top-down thickness variation called "golf-te ", wherein the sample is thicker at the top, The sample has a "golf tee" profile when viewed in the Y-section. Since the region of interest is typically contained near the upper surface of the lamella, a thicker dimension may cause the region of interest to be obscured, resulting in less than the desired sample for TEM observation.

 An example of a "golf-tee" effect can be seen in FIG. 8, which illustrates a TEM sample 50 comprising an ion beam induced deposition (IBID) tungsten protective layer 52 located on the top surface of the sample 50 . In this example, after thinning, the sample 50 is 44 nm wide just below the protective layer 52 and narrows to a width of 25 nm at 150 nm below the protective layer 52. This thickness variation is a result of different etch rates between the silicon substrate and the tungsten protective layer. Tungsten is a harder material than silicon and has a significantly lower etch rate, which makes the tungsten protective layer 52 wider than the lamellar body. Typically, the region of interest is located in a general region where "golf-tee" occurs and obscures or hinders the region of interest for TEM observations.

There is a need for an improved material deposition method for obtaining a controlled workpiece surface without surface artifacts and tilt changes.

It is an object of the present invention to provide an improved method and apparatus for forming a protective layer for charged particle beam processing to expose areas of interest for observation.

A charged particle beam processing system of a workpiece for exposing a region of interest for observation provides a precursor gas to the surface of the workpiece; Directing the charged particle beam toward the substrate to induce deposition of a protective layer over a region of interest, said at least two different materials having different sputter velocities from the precursor gas; And exposing the region of interest below the protective layer by milling the charged particle beam through the protective layer with the beam directed toward the substrate.

The foregoing has outlined the features and technical advantages of the present invention in a broader manner so that the following detailed description of the invention may be better understood. Additional features and advantages of the present invention will be described hereinafter. It should be appreciated by those of ordinary skill in the art that the disclosed concepts and specific embodiments may be readily utilized as a basis for modifying or designing other structures to accomplish the same purpose of the present invention. It is also to be appreciated by those of ordinary skill in the art that such equivalent constructions do not depart from the scope of the invention as set forth in the appended claims.

The present patent or application filed contains at least one drawing executed in color. A copy of the present patent or patent application publication having a color diagram shall be furnished by the Office upon request and payment of the required fee. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:
Figures 1 to 3 illustrate the steps in the preparation of ex-situ samples according to the prior art.
Figure 4 shows a prior art lamellar profile with a rigid diamond substrate and an easily consumable soft platinum top layer.
Figure 5 shows a prior art lamellar profile with a soft copper substrate and a hard carbon top layer, including the undercutting produced.
Figure 6 is a micrograph of a FIB cross section with a tungsten top layer representing the cutting, according to the prior art.
7 is a photomicrograph of a thinned TEM sample having a carbon top layer showing the cutting, according to the prior art.
Figure 8 shows a lamellar image after thinning with "Golf-T" artifacts, according to the prior art.
Figure 9 schematically depicts a charged particle beam system comprising a multiple gas injection system (MGIS).
Figure 10 shows a contour plot of the vertical deposition growth rate as a function of the valve duty cycle for the Pt precursor (X axis) and C precursor (Y axis).
Figure 11 shows a contour plot of the sputter rate of the deposited C-Pt composite material as a function of the valve duty cycle for the Pt precursor (X axis) and C precursor (Y axis).
Figure 12 shows a lamellar profile with a C-rich protective composite layer.
Figure 13 shows a lamellar profile with a Pt-rich protective composite layer.
FIG. 14 shows a lamellar profile having a C-Pt protective composite layer.
Figure 15 shows one embodiment of composite material deposition for a substrate having a formed via structure.
Figure 16 shows another embodiment of composite material deposition for a substrate having a formed via structure.
Figure 17 shows another embodiment of composite material deposition for a substrate having a formed via structure.
Figure 18 shows the valve duty cycle for the composite material deposition of Figure 17;
FIG. 19 shows another embodiment of composite material deposition for a substrate having a formed via structure.
Figure 20 shows the valve duty cycle for the composite material deposition of Figure 19;
Figure 21 shows another embodiment using a dual beam system of the type for carrying out the invention.
Figure 22 shows a lamellar profile with a protective layer of discrete material.
Figure 23 shows a lamellar profile with a protective layer of many different materials.
Figure 24 shows a lamellar profile with a protective layer of a separate alternating material.
Figure 25 shows an image of a preferred embodiment of a lamella with a plurality of protective layers.
Figure 26 shows a micrograph of another preferred embodiment of a lamellar having a plurality of protective layers.
Figures 27a and 27b show plots of data from Tables 1 and 2;
28 shows a flow diagram for material deposition according to the present invention.

Embodiments of the present invention provide an improved protective layer for charged particle beam processing by using two different materials to produce an improved protective layer.

According to one embodiment, material deposition is performed to provide a layer of protective material having a sputter rate that substantially matches the sputter velocity of the substrate material. The charged particle beam is directed from the vacuum chamber of the FIB system toward the substrate to induce material deposition from the precursor gas mixture. The resistance to sputtering of the protective layer material deposition can be controlled by varying the ratio of the gas mixture components. A multi-gas injection system with variable flow control and mixing capability is used that can vary the precursor ratio over a wide range to vary the hardness of the protective layer material depending on the material of the sample substrate.

According to another embodiment, material deposition is performed to provide a protective layer comprising two or more material compositions each layer deposited on a layer having a different etch rate. Preferably, the charged particle beam is directed towards the substrate in the vacuum chamber of the FIB system, leading to deposition of the first protective layer on the sample substrate, above the region of interest, from the precursor gas. The ion beam is then directed toward the sample substrate to induce deposition of at least a second passivation layer on top of the first passivation layer from the precursor gas. Advantageously, the first passivation layer has an etch rate that closely matches the etch rate of the sample, and the second passivation layer (and any additional layer) has an etch rate that is different from the etch rate of the sample. For example, in the case of a softer substrate, a softer protective material may first be deposited in direct contact with the substrate, and then a more rigid second layer may be deposited on top of the first layer. The more rigid layer will withstand erosion from the ion beam, and the softer bottom layer will prevent cross-section artifacts. A bottom layer having a sputter velocity matched closely to the sputter speed of the substrate reduces the risk of cross-sectional artifacts. In the case of a harder substrate, such as diamond, carbon or silicon carbide, a harder protective layer is first deposited in direct contact with the substrate, and a softer material layer may be deposited on top of the first layer.

In another embodiment, material deposition is performed to provide an alternating layer of material, such that the alternating thin layer of material is deposited using a separate gas chemistry so that the etch rate of the protective layer material forms a "tuned" , Which forms an alternating "parfait-like" macrostructure with an etch rate between the etch rates of the individual components. By adjusting the thickness of the individual components as well as the total number of layers, the user can achieve some degree of adjustability to achieve the desired film properties. A limited extreme ultrahigh-thickness alternating layer can be deposited, resulting in a deposit similar to the complex mixture.

In another embodiment, a mixture of gas precursors is used for material deposition, but during the deposition process the ratio of the gas is gradually adjusted to produce a composite capping material such that the bottom of the protective layer is primarily a component, It is mainly another component and includes an intermediate region having an intermediate composition. This provides a progressive transition from hard to soft (or vice versa) as the wheat progresses through the protective material.

In another embodiment, the method of depositing materials described herein adjusts the hardness of the sacrificial protective cap to prevent lamellar failure due to erosion from the beam tail and to reduce cross-sectional artifacts at the interface, such as, for example, And can be carried out in TEM lamellar manufacturing so as to be minimized.

In another embodiment, the material deposition method described herein can be performed using a composite capping layer to produce a cross-sectional FIB cross-section that generally includes a cut surface free of defects and tilt changes.

In another embodiment, the material deposition method described herein can be performed for the purpose of modulating a milled profile of high-aspect ratio structures (e.g., vias) produced by ion beam milling using a composition deposition film.

According to a first preferred embodiment of the present invention, a substrate, e.g. a semiconductor wafer, is loaded into a dual-beam FIB / SEM system having both a FIB column and a SEM column. Although a dual-beam system is discussed, it should be understood that other FIB systems may be used to carry out the present invention. The wafers may be moved manually or preferably by a multi-wafer carrier and a self-loading robot (not shown).

In applications for producing lamellar samples, the location of the sample phase area containing the form of interest for extraction and analysis (i. E., The lamellar site) is determined. For example, the substrate may be a semiconductor wafer or a portion thereof, and the sample to be extracted may comprise a portion of an integrated circuit that is observed using a TEM. Typically, the substrate is processed by using machine vision to place a reference mark on the wafer or wafer piece, or by using an edge and alignment notch or flat of the non-patterned wafer It is coarsely aligned. Alternatively, the lamella portion can be automatically positioned using image recognition software. Suitable image recognition software is available from Cognex Corporation (Matsik, MA, USA). Image recognition software may be "trained" to position the desired lamella location using a sample image of a similar feature or by using geometric information from CAD data. Automated FIB or SEM metrology can also be used to assist in identifying or identifying the lamella site. Metrology can consist of image-based pattern recognition, edge detection, ADR, center-of-mass computation, or blobs. If desired, the reference mark can be milled onto the substrate surface as a precise, accurate position mark.

A composite protective layer is then deposited on the lamella region to protect the sample. In a first preferred embodiment, the IBID or EBID deposition can be performed using a multiple gas injection system in which two or more precursor gases flow simultaneously. For example, a deposition can be performed in which the deposited material has properties that are intermediate to the two individual components. For example, IBID deposition obtained using a mixture of Pt and C precursors can be performed to obtain a protective layer having properties intermediate to those obtained using the Pt and C precursors separately. Precursor mixing can be performed in a number of ways. For example, a single gas nozzle outlet may be shared by two or more vessels containing individual chemical precursors, and the relative flow rate of the individual components may be controlled by a pulse valve located between the chemical precursor vessel and the outlet .

Figure 9 shows a schematic of a beam system 100 including an embodiment of the present invention. The beam system 100 includes a sample stage 104 for supporting a workpiece 106 to be processed by a beam generating subsystem, e.g., a beam 110 generated by a laser or a charged particle beam column, Includes a chamber (102). For example, the charged particle beam column 112 may include a charged particle source 113, one or more focusing lenses 114, and a beam 110 that scans or otherwise directs the beam 110 to a specified pattern on the workpiece surface And a current transformer 116 for rectifying the current. The combination of an exhaust system, such as a high vacuum turbo pump 120 and a back pressure pump 122, is preferably less than 10 ^-3 mbar, more preferably less than 10 ^-4 mbar, more preferably in the sample vacuum chamber 102 during processing Maintain a vacuum of about 10 ^-5 mbar or less. The back pressure pump 122 exhausts to the exhaust outlet 124.

The gas is supplied to the local area of the surface of the workpiece by a folding needle 130 extending from a multi-gas injection system (MGIS) valve 132, which is described in more detail below. A gas, such as a deposition precursor gas, an etch precursor gas, or an inert purge gas, is stored in the gas reservoir 131. The term " reservoir "is used extensively to include any gas source. A portion of the reservoir 131 may comprise a solid or liquid material, for example heated in a crucible, to generate the desired gas, and the other reservoir 131 may comprise a compressed gas. Each reservoir 131 is connected to an MGIS valve 132 by a corresponding conduit 133 including a regulating valve 134 and a stop valve 136 in the flow path between each reservoir 131 and the MGIS valve 132. [ ). Although Figure 9 shows two reservoirs with corresponding conduits, the present invention is not limited to any number of reservoirs. Some embodiments of the invention use more than six reservoirs, while other embodiments may use a single gas source.

The MGIS valve 132 needle 130 is extended and the process gas is introduced into the vicinity of the point where the charged particle beam 110 is focused through the needle 130 from the valve 132 To the surface of the workpiece 106 of FIG.

A sample stage 104 is used to position the workpiece below the charged particle beam 110 and the needle 130. The gas from the needle 130 in the sample vacuum chamber is eventually pumped from the chamber by the turbo pump 120. The vacuum pump 138 removes the remaining gas from the inside of the MGIS valve via the MGIS vacuum conduit 140 equipped with the MGIS vacuum valve 142.

A particular approach to the composite protective layer is to mix the precursors in a specific ratio according to the material of the sample substrate. Preferably, one of the precursors will yield a relatively soft deposition material, and the other precursor will yield a relatively hard deposition material. Thus, the user can adjust the hardness of the deposition layer to be between the characteristics of each individual precursor. The precursors are mixed in a ratio such that the sputter speed of the protective layer material matches the sputter speed of the substrate material to enable sufficient thinning and to avoid contact artifacts. The duty cycle of the valve in the MGIS delivery hardware may vary continuously from 0% to 100%. Thus, the deposition material can be adjusted to have properties that are intermediate between the properties of the individual mixed precursor components. This allows customized deposition for different substrate materials and different applications.

In one example, a carbon-platinum (C-Pt) protective layer is deposited. The C-Pt precursor is mixed at a specific ratio depending on the material of the substrate. This is accomplished by adjusting the C-Pt ratio as shown in the contour plots as shown in FIGS. 10 and 11. 10, a contour plot 150 of the vertical deposition growth rate (nm / sec) as a function of the valve duty cycle for the Pt precursor (X axis) and C precursor (Y axis) is shown. The highest growth rate is indicated by circle 152 and the growth rates of the standard single-precursor materials are indicated by circles 154 and circles 156 for Pt and C, respectively. A contour plot 160 of the sputter rate of the deposited C-Pt composite material is shown in Figure 11 as a function of the valve duty cycle for the Pt precursor (X axis) and C precursor (Y axis). The sputter rates of standard single-precursor materials are indicated by circles 162 and circles 164 for Pt and C, respectively. The conditions indicated by circle 166 when adding a small amount of Pt to most of the C deposition, for example, cause a superior material as a protective cap layer rather than a discrete component. The layer is much harder than Pt alone, but has no C-only cutting effect. The variable duty cycle valve control or the "use" time% of the pulse valve and the mixing capability of the multiple gas injection system enable this adjustment. Thus, the desired "hardness" can be achieved by moving from the top left to the bottom right of the contour plot 160 in FIG. Thus, the user can customize the hardness of the deposited layer to match the sample, particularly to match the hardness of the sample substrate.

  For example, as shown in Figures 12-14, C-Pt composite material deposition with various hardness characteristics is performed on the substrate. For example, the C-Pt composite material is formed on the substrate 200 by continuously adjusting the valve duty cycle to achieve a C-rich composite (C valve duty cycle = 80%, Pt valve duty cycle <2% , A very hard protective layer 202 (not as hard as C alone) as shown in FIG. As shown in FIG. 13, the C-Pt composite material is deposited on the substrate 206 by continuously adjusting the valve duty cycle to achieve a Pt-rich composite (C valve duty cycle <2%, Pt valve duty cycle = To create a very soft protective layer 208 (not as soft as Pt alone). When a hard substrate sample is used, such as diamond, a C-rich layer can be deposited having a hardness that closely matches the hardness of the diamond substrate. 14, a substrate 210 having a protective layer 212 of C-Pt material deposited with an MGIS setting of 80% -5% (C versus Pt) is obtained with pure C or pure Pt precursor Layer. The 80% -5% ratio has a higher material growth rate than the individual C or Pt used alone. In addition, this ratio has a higher sputter resistance than Pt and has a lessening of C than the C artifact.

Other depositions can be obtained for substrates having various hardness characteristics. For example, a protective layer having an intermediate duty cycle (e.g., 40% for both carbon and platinum) will have properties that are approximately intermediate to those obtained with the individual components. In the case of a sample having a softer substrate characteristic, such as an organic resin, the deposition precursor can be adjusted to be platinum-enriched.

Possible duty cycle and sample combinations use a medium hard silicon substrate with a deposition layer using a valve duty cycle of 50% -50% (C vs. Pt), a valve duty cycle of 80% -1% (C vs. Pt) And a soft resin substrate having a vapor deposition layer using a valve duty cycle of 5% -80% (C vs. Pt). The precursor may also be mixed with conventional MGIS systems wherein the ratio of the precursors can be roughly adjusted by controlling the crucible temperature of each agent. However, multiple duty cycle combinations are possible, and this example illustrates that the hardness of the deposited material can be continuously varied to match the hardness of the substrate material.

In addition to the pulse valve mixing strategy described above, other precursor delivery methods may be used. For example, the relative flow rate of the individual precursor components can be controlled by using a mass flow control valve, a metering needle valve, or simply by adjusting the temperature of the precursor vessel to adjust the vapor pressure of the component. The flow rate can also be influenced by using different sized holes (openings) or using pipes with different internal diameters. Finally, it is possible to mix the multiple precursor chemicals in the same vessel so that the opening of a single valve accommodates a mixture of precursor gases into the vacuum chamber of the apparatus. Regardless of the delivery strategy used to deliver the multi-component precursor mixture, the properties of the deposited material layer can be adjusted regardless of the hardware or system for producing the mixture using the precursor mixture.

The layer of deposition material from the precursor mixture can be applied for a variety of different applications. In TEM lamellar manufacturing, adjusting the hardness of the sacrificial protective cap can prevent lamellar breakage due to erosion from the beam tail and minimize cross-sectional artifacts at the interface, such as cutting and golf-tee, can do. Another use for composite material deposition is generally for use in creating cross-sectional FIB cross-sections with cut-outs free of defects and slope changes.

The composite deposition layer can also be used to control the milled profile of high-aspect ratio structures (e.g., vias) generated by ion beam milling. This may be useful for FIB nano- and micro-fabrication or ion-beam lithography techniques. As shown in FIG. 15 in the present application, the workpiece 250 includes a thin composite deposition capping material 252 deposited on a substrate 254 on which the user wishes to create a high-aspect ratio structure, ). The specific approach to composite deposition should be chosen to be "harder" than the underlying target material. When the mill is initially advanced, the ion beam will penetrate deeper into the hard deposit layer 252. Eventually, the mill will reach the interface between the rigid deposition 252 and the soft base substrate 254. At this point, the base substrate 254 will begin to be milled only in the center of the ion beam profile with the highest milling speed. Because the base substrate 254 is softer than the capping material 252 and the ion beam profile is a roughly Gaussian profile, the soft material 254 is quickly milled by the strong center of the ion beam distribution While the less powerful "tail" of the ion beam did not penetrate the harder capping material 252.

Thus, the arrangement of the harder capping film on the softer top of the target material has a sharpening effect on the shape of the ion milling probe, resulting in a vias with narrower dimensions that are achievable with a non-capped substrate It is possible. If desired, the top capping film could be removed at the final stage leaving behind the "sharpened" high aspect ratio mill. This could be achieved, for example, by using a hard carbon film on a silicon substrate and the carbon film could be removed using an oxygen plasma cleaning step. Thus, a high aspect ratio structure having a relatively narrow dimension and parallel sidewalls can be formed.

In another example, by depositing a capping film that is smoother than the underlying substrate, vias can be formed with a chamfered or tapered profile (open flared at the top) . In this example shown in FIG. 16, the workpiece 260 appears to have a capping layer 262 that is softer than the base substrate 264 that is formed with vias 266. The effect of the beam tail on the soft capping layer 262 will create more lateral erosion as compared to vias milled without a cap, resulting in significant expansion at the top of the via structure.

Figure 17 shows an embodiment of a workpiece 280 comprising a silicon substrate 281 with a composite layer 282 where FIB-milled vias 283 are generated, And "hardness" which varies from the bottom to the top of the layer. This composite layer can be created by adjusting the duty cycle of the individual precursor components during the deposition process. For example, a Pt-C composite layer can be deposited that changes from soft to hard (bottom to top) by starting the deposition with a Pt-rich mixture and gradually transitioning to a C-rich mixture as the deposition grows have. The valve duty cycle for this process is illustrated by graph 286 in FIG.

19 shows a reverse process using a workpiece sample 290 comprising a silicon substrate 291 with a composite layer 292 where FIB-milled vias 293 are produced, wherein the composite layer 292 is And "hardness" which varies from the bottom to the top of the layer. This composite layer can be created by adjusting the duty cycle of the individual precursor components during the deposition process. For example, a Pt-C composite layer that varies from hard to soft (bottom to top) can be deposited by starting the deposition with a C-rich mixture and gradually transitioning to a Pt-rich mixture as the deposition grows have. The valve duty cycle for this process is illustrated by graph 296 in FIG.

Although the Pt-C mixture is discussed as an example of a multiple layer, it should be understood that other precursor combinations may also result in a deposition layer with variable material properties. For example, carbon-platinum complexes can be obtained using precursors of naphthalene and (methylcyclopentadienyl) trimethylplatinum. The carbon-tungsten composite can be obtained using naphthalene and W (CO) ₆ precursors. A precursor of (methylcyclopentadienyl) trimethylplatinum and W (CO) ₆ can be used to obtain a platinum-tungsten composite, and a precursor of naphthalene and TEOS or TMCTS or HMCHS can be used to form a carbon- Complex can be obtained.

It is possible to control the "hardness" of the dielectric deposition, which is typically accomplished using a siloxane-based precursor and an oxidizing agent. A high concentration of oxidant will induce a deposition layer with a fully saturated SiO ₂ stoichiometry, but a layer of depleted oxidant will not fully saturate and will have a stoichiometry of SiO _x (X <2). Any of the following siloxane-oxidant combinations are suitable for this adjustment: TEOS (tetraethyl orthosilicate) and O ₂ ; TMCTS (tetramethylcyclotetrasiloxane) containing N ₂ O; And HMCHS (hexamethylcyclohexasiloxane) and water. However, any of the above siloxanes may be used with any of the above oxidizing agents.

In order to deposit a dielectric layer with variable hardness, any of the following primary ions: O ⁺ , O ₂ ⁺ , O ₃ ⁺ , N ⁺ , N ₂ ⁺ , H ₂ O ⁺ , H ₂ O ₂ ⁺ , N ₂ O ⁺ , NO ^{& lt} ; ⁺ & gt ^; , NO ^&lt; ₂ ^{+ &} gt ^; can potentially be used with the siloxane precursor. In this case, the oxidant may be the primary beam species itself. Thus, the deposited layer can be adjusted from the fully saturated SiO ₂ stoichiometry to the less saturated SiO _x stoichiometry by adjusting the beam current density, the precursor flux and / or the ion beam energy during the deposition process (X &lt; 2) stoichiometry.

It is to be understood that the above example discusses controlling the resistance to sputtering from the material "hardness" or ion beam, but other material properties can also be controlled using the same method. For example, the resistivity of a dielectric film will increase as the oxidant concentration increases. Thus, by controlling the siloxane-oxidant mixture, the user can deposit films with greater or lesser electrical conductivity. The optical transmittance of the deposited film is another property that can be controlled by precursor blending. In addition, material deposition using the disclosed method can be obtained by laser-assisted precursor decomposition or by thermal decomposition on a heated surface.

According to a second preferred embodiment of the invention, a substrate, e.g. a semiconductor wafer, is loaded into a dual-beam FIB / SEM system having both a FIB column and a SEM column. A typical dual-beam system configuration includes an electron column with a vertical axis and an ion column with an axis tilted relative to the vertical axis (typically of about 52 degrees). One such system is the DualBeam ^TM system of the Helios family, commercially available from the assignee of the present invention, FEI Company (Hillesboro, Oreg.).

Figure 21 shows a typical dual-beam FIB / SEM system 2110 suitable for practicing the present invention. The system 2110 includes an evacuated envelope having an upper neck portion 2112 with a liquid metal ion source 2114 or other ion source and a focusing column 2116 located therein. do. Other types of ion sources, such as multicusp or other plasma sources, as well as electron beams and laser systems, and other optical columns, such as shaped beam columns, may also be used.

The ion beam 2118 is transmitted from the liquid metal ion source 2114 through the ion beam focusing column 2116 and between the electrostatic deflection tools schematically represented in the deflection plate 2120 by a substrate or a workpiece 2122, For example, a semiconductor device located on the stage 2124 in the bottom chamber 2126). Stage 2124 may also support one or more TEM sample holders such that the sample can be extracted from the semiconductor device and moved to a TEM sample holder. The stage 2124 is preferably movable in a horizontal plane (X and Y axes) and vertically (Z axes). In some systems, the stage 2124 is also tilted by about 60 ° and can rotate about the Z axis. The system controller 2119 controls the operation of various parts of the FIB system 2110. Through the system controller 2119, a user can control that the ion beam 2118 is scanned in a desired manner through a command input to a conventional user interface (not shown). Alternatively, the system controller 2119 may control the FIB system 2110 in accordance with programmed instructions stored in a computer-readable memory, e.g., RAM, ROM, or magnetic or optical disk. The memory may store instructions for performing the method described above in an automated or semi-automated manner. The image from the SEM can be recognized by software for determining when to continue processing, when to stop processing, and where to position the beam for milling.

For example, a user may use a pointing device to describe a region of interest on a display screen, and then the system can automatically perform the steps described below for extracting samples. In some implementations, the FIB system 2110 includes image recognition software, such as commercially available software from Cognex Corporation (Matsik, MA, USA), to automatically identify regions of interest, The sample can be extracted manually or automatically according to the invention. For example, the system can automatically locate a similar shape on a semiconductor wafer comprising a plurality of devices, taking samples of this type onto different (or the same) devices.

An ion pump 2128 is used to evacuate the upper neck portion 2112. The bottom chamber 2126 is evacuated using a turbo molecular and mechanical pumping system 2130 under the control of a vacuum controller 2132. The vacuum system provides a vacuum of about ^{1 x 10 -7 Torr (1.3 x} 10 -7 mbar) to about ^{5 x 10 -4 Torr (6.7 x} 10 -4 mbar) in the bottom chamber (2126). In the case of the deposition precursor gas, or when an etch-assist gas or an etch-suppression gas is used, the chamber background pressure can typically rise to about 1 x 10 ^-5 Torr (1.3 x 10 ^-5 mbar).

The high voltage power supply 2134 forms an approximately 1 keV to 60 keV ion beam 2118 and is connected to a suitable electrode in the ion beam focusing column 2116 as well as a liquid metal ion source 2114 to direct it towards the sample. The deflection controller and amplifier 2136 operated in accordance with the predetermined pattern provided by the pattern generator 2138 is connected to the deflection plate 2120 so that the ion beam 2118 provided by the pattern generator 2138 is deflected Plate 2120 so that the ion beam 2118 can be manually or automatically controlled to look for a trace of a corresponding pattern on the upper surface of the workpiece 2122. [ In some systems, the deflector plate is positioned before the final lens as is well known in the art. A beam blanking electrode (not shown) in the ion beam focusing column 2116 is used to cause the ion beam 2118 to move to the target 2122 when a blanking controller (not shown) applies a blanking voltage to the blanking electrode. Instead, an impact is applied on the blanking opening (not shown).

The liquid metal ion source 2114 typically provides a gallium metal ion beam. The source for the purpose of imaging of the work piece 2122 to ion milling, promoting the etching, or the to-be-modified by the material deposited to the workpiece 2122, typically from 10 ^-1 to the processing member 2122 microns Can be focused into a wide beam. The charged particle detector 2140 is coupled to a video circuit 2142 that provides a drive signal to the video monitor 2144 to detect secondary ions or electron emissions and to be used to receive a deflection signal from the controller 2119 .

The location of the charged particle detector 2140 in the bottom chamber 2126 may vary in various implementations. For example, the charged particle detector 2140 may be coaxial with the ion beam and includes a hole for the ion beam to pass through. In other embodiments, secondary particles may be collected through the final lens and then diverted off the axis for collection. A scanning electron microscope (SEM) 2141 is optionally provided with the FIB system 2110 together with its power supply and controller 2145.

A gas delivery system 2146 extends into the bottom chamber 2126 to introduce and direct gas vapors toward the workpiece 2122. U.S. Patent No. 5,851,413 (Casella et al., "Gas Delivery Systems for Particle Beam Processing") assigned to the assignee of the present invention describes a suitable gas delivery system 2146. Another gas delivery system is described in U.S. Patent No. 5,435,850 (Rasmussen, "Gas Injection System ", also assigned to the assignee of the present invention). For example, the iodine may be delivered to enhance etching, or the metal organic compound may be delivered to deposit the metal.

A micro-manipulator 2147, such as an EasyLift micro-manipulator from F.I.A., the assignee of the present invention (Hillesboro, Oreg., USA), can precisely move an object within the vacuum chamber. The micromanipulator 2147 may include a precision motor 2148 located outside the vacuum chamber to provide X, Y, Z and theta control of the portion 2149 located within the vacuum chamber. The micro manipulator 2147 may have different end effectors for manipulating small objects. In the embodiment described below, the end effector is a thin probe 2150. The thin probe 2150 may be electrically coupled to a system controller 2119 for applying charge to the probe 2150 to control attraction between the sample and the probe.

The door 2160 is open to insert the workpiece 2122 onto the X-Y stage 2124 (which can be heated or cooled) and, if used, also to provide an internal gas supply reservoir. The door is interlocked so that it can not be opened if the system is under vacuum. In some embodiments, a standby wafer handling system may be used. The high voltage power supply provides an appropriate acceleration voltage to the electrodes in the ion beam focusing column 2116 to power and focus the ion beam 2118. When the ion beam hits the workpiece 2122, material is sputtered, i. E., Physically, from the sample. Alternatively, the ion beam 2118 can decompose the precursor gas to deposit the material. The focused ion beam system is commercially available, for example, from the assignee of the present application, F.I.Company (Hillesboro, Oreg.). While examples of suitable hardware are provided above, the present invention is not limited to being implemented in any particular type of hardware.

In this embodiment, material deposition can be performed by forming two or more separate layers of protective capping material. The user may choose to initially deposit the "softer" material in direct contact with the underlying substrate, and then a second, "harder" layer may be deposited on top of the first layer. The harder top layer will withstand erosion from the ion beam, and a softer bottom layer will prevent cross-section artifacts. In particular, if the bottom layer can be selected to match the sputter speed of the base material, the risk of cross-section artifacts can be minimized. In other cases, the order may be reversed such that a harder material is first deposited first, followed by a more flexible material. This arrangement may be preferred when the FIB mills hard materials such as diamond, carbon or silicon carbide.

For example, as shown in FIG. 22, a lamellar substrate 1200 is preferably used to prevent damage to the upper region of the substrate 1200 near the top surface where the region of interest is typically located, Has a protective layer of material having a bottom layer 1202 deposited initially on the top surface of the substrate 1200 using inductive deposition (EBID). The alternative is to use an IBID of low energy (< 8 keV), which also causes very low damage to the top surface. In some processes, low energy FIB deposition is used rather than EBID. This first bottom layer material 1202 is selected to match as closely as possible to the etch rate of the substrate 1200 material in a < 5kV FIB of a glancing angle operating system, especially between 10 and 45 degrees off. Silicon (Si) - For the described sample, this bottom layer 1202 is preferably a silicon oxide material type, for example, TEOS (IDEP), TEOS + H ₂ 0 (IDEP2), TEOS + O _2, HMCHS, HMCHS + O ₂ (IDEP3), a HMCHS / H ₂ O and _{HMCHS / N 2 O, TMCTS,} TMCTS + O 2, and / or _{TMCTS / H 2 O, TMCTS /} N 2 O. The top layer material 1204 is then deposited on top of the bottom layer 1202 using ion beam induced deposition (IBID). The top layer material 1204 is selected to have a lower etch rate than the substrate 1200 material to provide protection during the lamellar thinning process and to prevent artifacts from being formed on the outer surface of the sample.

If desired, more than one top layer may be deposited. The top layer or layers are preferably tungsten, carbon or platinum. As an example, carbon has excellent resistance to low-kV FIB milling, which contributes to excellent protection, but has significant internal stress that can bend the lamella. Thus, a pure carbon layer is undesirable. 23, the substrate 1300 has a protective layer comprising a bottom layer 1302 of a material similar to the layer 1202 discussed with respect to FIG. A thin carbon layer 1304 (e.g., a 100 nm C layer after 30 kV treatment) on top of a thicker tungsten layer 1306 (e.g., about 400 nm) is better than a tungsten alone by a low-kV FIB irradiation And the tungsten will provide stiffness to the lamella. In the grazing area of the FIB beam impinging the FIB beam to the lamella side walls, the silicon substrate etch rate increases dramatically compared to tungsten, which is typically less than the golf- Te effect. The qualitative plots of angle-dependent sputtering rates of silicon and tungsten are shown in the following table.

Tables 1 and 2 below show the sputter and volume yields from 5 kV gallium ions. The data from Tables 1 and 2 are tabulated in Figures 27A and 27B.

Sputter yield (SRIM) Volume yield, nm ³ / ion bracket Si W Si W 45 4.08 6.82 6.44E-05 1.37E-04 50 5.01 7.07 7.90E-05 1.42E-04 55 6.46 7.14 1.02E-04 1.43E-04 60 8.14 7.24 1.28E-04 1.45E-04 62 8.87 7.17 1.40E-04 1.44E-04 64 9.4 7.6 1.48E-04 1.53E-04 66 10.08 7.53 1.59E-04 1.51E-04 68 10.99 7.54 1.73E-04 1.51E-04 70 11.6 7.44 1.83E-04 1.49E-04 75 12.94 7.29 2.04E-04 1.46E-04 80 13.22 6.55 2.09E-04 1.32E-04 82 12.63 6.1 1.99E-04 1.23E-04 84 12.09 5.65 1.91E-04 1.14E-04 85 11.47 5.47 1.81E-04 1.10E-04 86 10.68 5.04 1.69E-04 1.01E-04 87 9.992 4.72 1.58E-04 9.48E-05

The sputter rate for Si at 45 [deg. bracket Si W 45 1.00 2.13 40 1.23 2.21 35 1.58 2.23 30 2.00 2.26 28 2.17 2.24 26 2.30 2.37 24 2.47 2.35 22 2.69 2.35 20 2.84 2.32 15 3.17 2.28 10 3.24 2.04 8 3.10 1.90 6 2.96 1.76 5 2.81 1.71 4 2.62 1.57 3 2.45 1.47

In another embodiment of the multilayer deposition strategy, a plurality of layers can be deposited in an alternating configuration. The lamination of multiple layers of different deposition materials can, on average, result in a layer having intermediate properties of the two individual components. By adjusting the thickness of the individual components as well as the total number of layers, the user can achieve some degree of coordination to achieve the desired properties of the layer. Typically, the desired film properties are in the middle of the individual components. For example, if platinum is too soft and the carbon is too hard for a particular application, multilayer deposition of alternating platinum and carbon deposits may be preferred over either homogeneous layer of individual components.

24 illustrates an embodiment of material deposition in which the substrate 1400 includes a protective layer 1402 having alternating layers of materials 1404 and 1406 wherein the etch rate of the protective layer material 1402 is a separate gas Is "tuned" by depositing alternating thin layers of material 1404 and 1406 using chemistry, which forms an alternating "parfait-like" macrostructure with an etch rate that is between the etch rates of the individual components.

25 shows a tungsten layer 1504 for visual observation of the top of the substrate 1500 and the contour depiction between the SEM deposited silicon oxide layer 1506 and the sacrificial protective layer 1502 which is the top layer 1508 of tungsten. And a sacrificial protective layer 1502 of a separate layer containing a sacrificial protective layer 1502. As can be seen, a "golf tee" effect occurs in the sacrificial protective layer 1502 after thinning, but does not occur within the substrate 1500.

26 shows a silicon lamella with an EBID TEOS layer, an IBID tungsten layer and an IBID carbon layer.

In the embodiment of Figures 12 to 16, the sacrificial protection layer having a similar etch rate to the substrate sample moves the golf tee up in the protective layer and away from the top of the substrate containing the region of interest for analysis and analysis.

As shown in FIG. 28, the present invention provides a method of material deposition in which a sample is loaded into a selected beam system (1600). At least two precursor gases are provided for material deposition (1602). At decision block 1604, it is determined whether to deposit the material as a separate layer or as a multiple layer. If a separate layer is deposited (1606), a first layer is deposited (1608) on the sample and then another layer is deposited (1610). If only two layers are desired to be deposited, a decision to end 1612 is made at 1616, and the process is complete 1618. If more than two layers are to be deposited, then a decision is made to not end 1614 and the process returns to block 1608 and a determination 1616 is made to end 1618 to complete the process. It continues until it does. If a composite layer is to be deposited 1620, at least two precursor gases are mixed 1622 according to the determined scheme and the composite layer is deposited 1624 onto the sample, do.

Some embodiments of the present invention

Providing a precursor gas to the surface of the workpiece;

Directing the charged particle beam toward the substrate to induce deposition of a protective layer over the region of interest, the protective layer consisting of at least two different materials having different sputter velocities from the precursor gas; And

Directing the charged particle beam toward the substrate and passing through the protective layer and milling to expose the region of interest below the protective layer

A method for processing a charged particle beam of a workpiece for exposing a region of interest for observation.

In some embodiments, the step of providing a precursor gas to the surface of the workpiece and directing the charged particle beam toward the substrate to induce deposition of a protective layer from the precursor gas

Providing a first precursor gas to the surface of the workpiece;

Directing a charged particle beam toward the substrate to induce deposition of a first material having a first sputter rate from the first precursor gas;

Providing a second precursor gas to the surface of the workpiece; And

Directing the charged particle beam toward the substrate to induce deposition from the second precursor gas of a second material having a second sputter rate from a second precursor gas;

Thereby forming a protective layer having the first material layer and the second material layer

.

In some embodiments, the first material comprises silicon oxide.

In some embodiments, the second material comprises tungsten, carbon, or platinum.

In some embodiments, the protective layer comprises a layer of alternating material.

In some embodiments, directing the charged particle beam toward the substrate and passing through the protective layer and milling to expose the region of interest below the protective layer comprises fabricating a lamella having a thickness of less than 200 nm .

In some embodiments, the sputter velocity of the first material is matched to the sputter velocity of the workpiece, and the sputter velocity of the second material is lower than the sputter velocity of the workpiece.

In some embodiments, providing the precursor gas to the work surface protection layer comprises providing a mixture of multiple gas species.

In some embodiments, the mixture of multiple gas species comprises a mixture of a platinum precursor and a carbon precursor.

In some embodiments, the mixture of multiple gas species comprises a mixture of a platinum precursor and a silicon oxide precursor.

In some embodiments, the relative amount of the multi-species gas species in the mixture of multi-species gas species varies during deposition of the protective layer, thereby providing a protective layer having a different composition at different depths of the protective layer.

In some embodiments, the portion of the protective layer at the surface of the workpiece is softer than the top portion of the protective layer.

In some embodiments, directing the charged particle beam toward the substrate and passing through the protective layer and milling to expose the region of interest below the protective layer may include exposing the cross-section of the portion of the workpiece for observation on a scanning electron microscope .

Some implementations

An ion beam system including an ion beam source;

An ion optical column for focusing the ion beam onto the substrate;

A gas source for providing a precursor gas to the surface of the workpiece;

A processor for controlling the focused ion beam system according to stored instructions; And

A computer-readable memory for storing computer instructions for performing the methods described above,

To provide a focused ion beam system for analyzing a workpiece.

It is to be appreciated that the substrate relates to the deposition of a protective layer, which is primarily robust and repeatable and suitable for automation, but that the apparatus for carrying out the operation of the method may further be within the scope of the present invention. Although it has been described that the material deposition method is performed using a dual-beam system, it should be understood that the material deposition method described herein can be performed by a standard-only SEM system or a standard-only FIB system of any ionic polarity do. It should also be appreciated that most of the beam deposits are not completely pure and may contain "impurities ", such as precursor fragments, hydrocarbon inclusions, voids, and dense deformation that can cause deviations from the theoretical model of sputter hardness. It should also be appreciated that implementations of the invention may be implemented via computer hardware or software, or a combination of both. The method is a computer program using standard programming techniques comprising a computer-readable storage medium comprising a computer program, wherein the storage medium is configured to operate in a predetermined, predefined manner, Can be executed according to the drawings. Each program can be executed in a high-level procedural or object-oriented programming language for communicating with the computer system. However, the program may be executed in assembly or machine language, if desired. In any case, the language may be an edited or interpreted language. In addition, the program may be executed on dedicated integrated circuits programmed for such purposes.

The preferred method or apparatus of the present invention has a number of novel aspects and not all aspects need to be present in all implementations since the invention can be implemented in different ways or apparatuses for different purposes. In addition, many aspects of the above described embodiments may be individually patentable. The present invention has broad applicability and can provide a number of advantages as described and illustrated in the above examples. The above embodiments will vary greatly depending on the specific use, and all embodiments will provide all of the advantages achievable by the present invention and will not satisfy all of the objects.

It should be appreciated that implementations of the invention may be implemented by computer hardware, a combination of both hardware and software, or by computer instructions stored in non-transitory computer-readable memory. The method is a computer program using standard programming techniques including a non-transitory computer-readable storage medium comprised of a computer program, wherein the storage medium is configured such that the computer is operated in a specific predefined manner. May be carried out according to the methods and drawings described. Each program can be executed in a high-level procedural or object-oriented programming language for communicating with the computer system. However, the program may be executed in assembly or machine language, if desired. In any case, the language may be an edited or interpreted language. In addition, the program may be executed on dedicated integrated circuits programmed for such purposes.

The methodology may also be implemented in a personal computer, a mini-computer, a mainframe, a workstation, a networking or distributed computing system, which is a computer platform separated from, embedded in or connected to a charged particle tool or other imaging device, Or any other type of computing platform including, but not limited to, a &lt; / RTI &gt; environment. Aspects of the present invention can be removed or stored on a non-transitory storage medium or device, whether or not embedded in the computing platform, such as a hard disk, optical read and / or write storage medium, RAM, ROM, So that it is readable by a programmable computer to configure and operate the computer to perform the procedures described herein when the storage medium or device is read by a computer. In addition, the machine-readable code or a portion thereof may be transmitted over a wired or wireless network. The invention described herein includes such and other various types of non-transitory computer-readable storage media if such medium contains instructions or programs for carrying out the steps described above, in conjunction with a microprocessor or other data processor do. The invention also includes the computer itself when programmed according to the methods and techniques described herein.

The terms "workpiece", "sample", "substrate" and "sample" are used interchangeably in this application unless otherwise specified. In addition, whenever the terms "automatic," "automated," or similar terms are used herein, such terms will be understood to include passive operation of the automated or automated process or step.

In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion and thus include, but are not limited to, " Should be construed as meaning. To the extent that any term is not specifically defined herein, the intention is to provide the term in its ordinary ordinary sense. The accompanying drawings are intended to aid in the understanding of the invention and are not to scale unless otherwise specified. Particle beam systems suitable for carrying out the present invention are commercially available, for example, from AIFI COMPANY, the assignee of the present application.

While the invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments described herein without departing from the scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described herein. It will be appreciated that those skilled in the art will readily appreciate that many modifications are possible, without departing from the scope of the present invention, as will be readily appreciated by one of ordinary skill in the art. , Composition of matter, means, method, or steps may be utilized in accordance with the present invention. Accordingly, the appended claims are intended to include within their scope such process, machine, manufacture, composition of matter, means, method or step.

Claims (14)

Providing a precursor gas to the surface of the workpiece;
Directing the charged particle beam toward the substrate to induce deposition of a protective layer over the region of interest, the protective layer consisting of at least two different materials having different sputter rates from the precursor gas; And
Directing the charged particle beam toward the substrate and passing through the protective layer and milling to expose the region of interest below the protective layer
To expose a region of interest for observation. &Lt; Desc / Clms Page number 19 &gt; The method of claim 1, further comprising the steps of providing a precursor gas to the surface of the workpiece and directing the charged particle beam toward the substrate to induce deposition of a protective layer from the precursor gas
Providing a first precursor gas to the surface of the workpiece;
Directing a charged particle beam toward the substrate to induce deposition of a first material having a first sputter rate from the first precursor gas;
Providing a second precursor gas to the surface of the workpiece; And
Directing the charged particle beam toward the substrate to induce deposition from the second precursor gas of a second material having a second sputter rate from the second precursor gas;
Thereby forming a protective layer having the first material layer and the second material layer
&Lt; / RTI &gt; 3. The method of claim 2, wherein the first material comprises silicon oxide. 4. The method of claim 2 or 3, wherein the second material comprises tungsten, carbon or platinum. 4. The method of claim 2 or 3, wherein the protective layer comprises a layer of alternating material. 4. The method of claim 2 or 3, wherein the sputter velocity of the first material matches the sputter velocity of the workpiece, and the sputter velocity of the second material is less than the sputter velocity of the workpiece. 2. The method of claim 1, wherein providing the precursor gas to the work surface protection layer comprises providing a mixture of multiple gas species. 8. The method of claim 7, wherein the mixture of multiple gas species comprises a mixture of a platinum precursor and a carbon precursor. 8. The method of claim 7, wherein the mixture of multiple gas species comprises a mixture of a platinum precursor and a silicon oxide precursor.  10. A method according to any one of claims 7 to 9, characterized in that the relative amount of the multiple species of gas in the mixture of multiple gas species varies during the deposition of the protective layer, thus having a different composition at different depths of the protective layer Thereby providing a protective layer. 10. The method of any one of claims 2-7, wherein the portion of the protective layer at the surface of the workpiece is softer than the top portion of the protective layer. 10. A method according to any one of claims 1 to 3 or 7 to 9, wherein the charged particle beam is directed toward the substrate and passes through the protective layer and milled to expose the region of interest below the protective layer Wherein the step comprises producing a lamella having a thickness of less than 200 nm. 10. A method according to any one of claims 1 to 3 or 7 to 9, wherein the charged particle beam is directed toward the substrate and passes through the protective layer and milled to expose the region of interest below the protective layer Wherein the step comprises fabricating a cross-section of the workpiece portion for observation on a scanning electron microscope. An ion beam system including an ion beam source;
An ion optical column for focusing the ion beam onto the substrate;
A gas source for providing a precursor gas to the surface of the workpiece;
A processor for controlling the focused ion beam system according to stored instructions; And
A computer-readable storage medium storing computer instructions for performing the method according to any one of claims 1 to 3 or 9 to 9.
Wherein the system is adapted to analyze a workpiece.

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